Conditions for Setting the DTC: P2721
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The TCM detects high voltage on the clutch PC solenoid 4 control circuit for 300 milliseconds in a 375 millisecond sample.